Nokea
Which of the following structures of the heart is called the pacemaker of the heart?
- A. AV junction
- B. SA node
- C. AV node
- D. Purkinje fibers
Correct Answer: B
Rationale: The sinoatrial (SA) node initiates and regulates the heartbeat, acting as the heart's natural pacemaker.
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What is a surgical procedure to replace a damaged or diseased heart valve with a prosthetic valve?
- A. Valve replacement
- B. Angioplasty
- C. Stent placement
- D. Bypass surgery
Correct Answer: A
Rationale: The correct answer is A: Valve replacement. This surgical procedure involves replacing a damaged or diseased heart valve with a prosthetic valve to restore proper heart function. It is specifically targeted at addressing heart valve issues, making it the most appropriate choice. Angioplasty (B) is a procedure to open blocked arteries, not related to heart valve replacement. Stent placement (C) involves inserting a mesh tube to keep arteries open, not addressing heart valve issues. Bypass surgery (D) is performed to improve blood flow to the heart muscle, not focused on replacing heart valves. Thus, A is the correct choice for the given question.
A patient has been receiving a heparin sodium IV for the last three days. The patient's most current platelet count is 65,000 × 103/uL; while the platelet count on admission was 350,000 × 103/uL. The cardiac-vascular nurse contacts the physician to:
- A. report that the medication level is subtherapeutic.
- B. report that the patient is exhibiting signs of an adverse reaction.
- C. request an increase in the medication infusion rate.
- D. request an order for platelet transfusion.
Correct Answer: B
Rationale: A significant drop in platelets suggests heparin-induced thrombocytopenia, an adverse reaction.
Which term conceptualizes that the greater the myocardial fiber stretch, within physiologic limits, the more forceful the ventricular contraction, thereby increasing stroke volume?
- A. Frank-Starling's Law
- B. Automaticity
- C. Contractility
- D. Excitability
Correct Answer: A
Rationale: The correct answer is A: Frank-Starling's Law. This law states that within physiologic limits, the greater the myocardial fiber stretch, the more forceful the ventricular contraction, leading to increased stroke volume. This is because increased fiber stretch results in optimal overlap of actin and myosin filaments in the sarcomeres, enhancing contractile force.
Summary:
B: Automaticity refers to the ability of cardiac cells to spontaneously generate electrical impulses.
C: Contractility is the intrinsic ability of cardiac muscle to generate force.
D: Excitability refers to the ability of cardiac cells to respond to electrical stimuli.
What is a condition where the lungs become stiff and scarred, making it difficult to breathe and get enough oxygen into the bloodstream?
- A. Pulmonary fibrosis
- B. Pulmonary edema
- C. Pulmonary embolism
- D. Pulmonary hypertension
Correct Answer: A
Rationale: Pulmonary fibrosis is the correct answer because it is a condition characterized by stiff and scarred lungs, leading to breathing difficulties and reduced oxygen intake. This occurs due to the formation of excessive connective tissue in the lungs, impairing their ability to expand and contract properly. Pulmonary edema is the accumulation of fluid in the lungs, not scarring. Pulmonary embolism is the blockage of a blood vessel in the lungs by a blood clot. Pulmonary hypertension is high blood pressure in the arteries of the lungs, not related to lung stiffness or scarring.
Which of the following adverse effects should a nurse check for when administering lidocaine?
- A. Convulsions
- B. Amnesia
- C. Dyspnea
- D. Urinary retention
Correct Answer: A
Rationale: Convulsions are a serious adverse effect of lidocaine toxicity, requiring vigilant monitoring.